Conveyance construction



May 12, 1964 COLLINS 3,132,605

CONVEIYANCE CONSTRUCTION Filed May 12, 1961 2 Sheets-Sheet 1 FIGI INVENTOR TAPPAN COLLINS ATTORNEYS.

- T. COLLINS May 12, 1964 CONVEYANCE CONSTRUCTION 2 Sheets-Sheet 2 Filed May 12, 1961 FIG 5 FIG 7 INVENTQR TAPPAN COLLINS BY M W ATTORNEYS.

FIG. 6

United States Patent I 3,132,6ti5. CUNVEYANCE CGNSTRUCTION Tappan Collins, Prairieton, Ind., assignor to National Steel Corporation, a eorporation of Delaware Filed May 12, 1961, Ser. No. 1%,759 16 Ciairns. (Cl. 1(l5-422) The present invention relates generally to freight carrying conveyances and more particularly to the structure of the flooring of such conveyances.

For many years, in freight conveyances such as railway rolling stock, all-steel freight cars of the open top variety had been used provided with floors comprised of steelplates fastened together. These gondola cars, as they are called, were fairly satisfactory for the transportation of freight of a loose nature such as coal, grain, iron ore, pig iron, or steel scrap or the like. Loose freight could simply be dumped into the car and transported without securernent of any kind, the steel floor providing underlying support for the freight and nothing more.

However, for those types of lading which needed to be immobilized with respect to the freight car for satisfactory transportation and those which needed floating or restrained connection with the car, wooden freight car floors had long been the only practical solution in both open top and box cars. In order to immobilize freight or to set it up in floating relation to such Wooden flooring of freight cars, various blocking arrangements were used. Heavy wooden blocking was placed in a position on the car floor where it would abut against the proper part of the lading and this heavy blocking was nailed in this position to the wooden floor with heavy nails. When the freight reached its destination, the blocking was ripped up in order to remove the freight from the car.

The old steel plate floors, which obviously could not be used in connection with blocking, had fairly long life. On the other hand, wood car floors did not. The impact forces of loading and unloading using heavy clamshell buckets and magnets in open top cars and the fork trucks used for loading and unloading box cars soon ruined the wooden flooring. Moreover, wooden flooring continuously used for blocking freight deteriorated rapidly due to weakening by the numerous nail holes.

Thus, the railroads were obliged to buy two kinds of cars, steel floor and wood floor. But this initial double expense was not the only disadvantage, as the steel cars and wood cars often ran empty. For example, in the steel industry, pig iron and scrap steel came into the plants in the old steel bottom cars and the finished product packaged to prevent damage in transportation went out in wooden bottom cars. Most of the time the wooden bo tom cars came in empty and the steel bottom cars went out empty because neither type of car alone could handle both types of freight.

In an effort to provide a single all-purpose, stronger freight car flooring, it was proposed quite some time ago to provide steel flooring having inserts comprising-wooden nailing strips, as in US. Patents Nos. 986,422 of 1911 and 2,056,137 of 1936, in the hope of combining the strength of steel with the nailability of wood. However, in spite of the great additional expense involved, this solution has not been satisfactory because the nail holes were concentrated in the inserted strips with the result that the wood broke up and deteriorated very rapidly. Furthermore,

3,132,6ti5 Patented May 12., 196d all attempted combinations of wood and steel have resulted in inordinate steel corrosions, possibly because the wood retains moisture and holds it in contact with steel surfaces.

In recent years, an all-metal flooring has been developed which is strong and has good nailing properties. This flooring is described in US. Patent No. 2,665,243 and comprises metal structural members arranged side-by-side to form the flooring of a freight conveyance. These structural members as illustrated in that patent have reinforcing Webs along their opposite sides and one web is provided with a male corrugationwhile the other web is provided with a complementary female corrugation. When the structural members are arranged side-by-side, the male and female corrugated members are in opposed spaced apart relationship to define therebetween a sinuous groove into which nails can be driven and gripped.

This recent metal flooring has been a vast improvement over any freight car flooring known theretofore. Nevertheless, it has been susceptible to various improve ments to strengthen it and render it cheaper and easier to manufacture, and the present invention embodies several such improvements.

Accordingly, it is an object of the present invention to provide a conveyance flooring adapted to receive and re tain nails, having improved strength characteristics under static or shock loads applied normal to the plane of the freight-engaging surface of the flooring.

Another object of the present invention is the provision of flooring for freight conveyances, adapted to receive and retain nails, which has highstrength per unit of crosssectional area, thereby to enable the use of lighter and less expensive flooring than in the past.

The invention also contemplates all-metallic flooring for freight conveyances, adapted to receive and retain nails within nailing slots having novel provision for retaining the nails within the slots. 1

Finally, it is an object of the present invention to pro- Vide freight conveyance flooring which will be easy and inexpensive to manufacture and install and rugged and durable in use.

Other objects and advantages of the present invention will become apparent from a consideration of the following description, taken in connection with the accompanying drawings, in which:

FIGURE 1 is a fragmentary perspective View of the interior of a lower corner of conveyance construction according to the present invention as embodied for example in a railway freight car FIGURE 2 is an enlarged fragmentary perspective exploded view of freight car flooring according to the view of a portion of a flooring member showing another modification of the present invention; and

FIGURE 7 is a view similar to FIGURE 4 but showing the embodiment of FIGURE 6.

Although the present invention is illustrated and will hereinafter be described in connection with railway rolling stock, it will be appreciated that it is susceptible of embodiment in conveyances of other types such as motor trucks, ships and the like. Although the illustrated embodiments indicate the use of an integral hot or cold rolled sheet metal structural member in the combination of the invention, the flooring members can have a variety of forms and can for example be in the form of extrusions or can be built up of component parts.

Referring now to the drawings in greater detail, there is shown in FIGURES 1-5 a first embodiment of the present invention, in the form of railway rolling stock comprising a conventional freight car of open top or box car type having a novel floor construction 1, side wall construction 3 and end wall construction 5. Side walls 3 are considerably longer than end walls 5, so that the freight car, as is usual, is elongated in its direction of travel. Supporting structure for the floor is provided comprising an underframe or floor supporting structure including frame members 6 running lengthwise of the car. The freight car rolls on the usual Wheels 7 on railroad tracks 8.

The floor carried by the conveying supporting structure comprises in the illustrated embodiments, a plurality of long, narrow contiguous metal structural members 9 arranged side-by-side and extending across the car transversely of the length of the car and supported on frame members 6. In order to provide a floor to withstand the hard usage to which it will be subjected in a freight conveyance such as a freight car, the structural members 9 are preferably formed of steel. Each member 9, in the illustrated embodiments, has a flat panel 11 on the upper side of the floor, and each flat panel 11 has a uniplanar freight-engaging face directed away from the conveying supporting structure, the freight-engaging faces of the plurality of structural members 9 being arranged at a uniform level to provide a uniplanar freight-engaging surface of the floor.

Each of the illustrated structural members 9 has a pair of downwardly extending side reinforcing webs 13 joined to the side edges of panel 11 through fillets of metal 14, the webs and fillets extending longitudinally of the panel. Flanges 15 extend laterally from the edges of the side reinforcing webs remote from panel 11 to provide reinforcement and seating surfaces for seating on the frame members 6 or other supporting structure of the conveyance. Fillets 16 join webs 13 and flanges 15. Fillets 14 and 16 preferably have as small a radius of curvature as possible consistent with a satisfactory condition of the metal of the fillet where cold forming or hot rolling is used. Where material 'of the flooring members is extruded the external corners at the fillets are as close to 90 as is practicable. The flooring is integrated with the conveying supporting structure by means of welds 23 by which at least some of the flanges 15 are secured to frame members 6, or by means of riveting or bolting or the like. Webs 13 have outer surfaces which are disposed in parallel planes perpendicular to the plane of panel 11. The two flanges of each illustrated structural member 9 extend toward each other and are coplanar, the common plane of these two flanges being parallel to the plane of panel 11 and perpendicular to the two parallel planes of webs 13. A hat-shaped rib 17 extends lengthwise of the mid-portion of and is secured to the underside of panel 11 as by welding or the like for reinforcement purposes.

The opposed adjacent flat surfaces of adjacent structural members 9, which are carried by webs 13 in the illustrated embodiments, are parallel to each other and vertical and are spaced apart about a quarter of an inch.

4 Unlike other types of flooring adapted to receive nails, however, webs 13 do not deform the nails, for the nails pass between the opposed surfaces of webs 13 without necessarily making mutual contact with both those surfaces.

Between opposed parallel adjacent flat surfaces, which in the illustrated forms are webs 13, is a body of solid elastic deformable material 19 which coacts with webs 13 to provide means for retaining nails in the nailing slot between opposed surfaces of Webs 13. Material 19 is in the form of a pair of strips 2% one intimately bonded in any suitable manner to each of the opposed outer web surfaces of a pair of adjacent members 9. Strips 20 meet in an interface 21 parallel to and equally spaced between each of the adjacent opposed web faces. A nail point guiding valley is formed by rounded edges 22 on the upper margins of strips 20 for the purpose of guiding nails initially into and along interface 21 between strips 20, so that the nails passing along interface 21 between strips 20 displace the material of strips 20 laterally, thereby permitting strips 20 to grip the nail between them in a tight frictional grip.

The adhesive by which material 19 is bonded to webs 13 may be that of the material itself when applied in plastic condition or may be separated adhesive, for example be in the form of any suitable adhesive or cement. Any of the epoxy resins useful in bonding plastics to metal can be used in such case. It is contemplated that where the members are hot formed or subjected to heat treatment the residual heat may be utilized to cure a thermosetting form of cement. With such practice a strip 20 would be applied to the outer surface of each web 13 in the steel plant itself after hot forming or heat treatment.

The body of material 19 is several times greater in height than in width and extends at least a major portion of the length of the adjacent members 9 which is exposed to the interior of the conveyance. Each strip 20 is preferably formed as a single unit but may be made up of a number of separate pieces disposed in end-to-end relationship along the length of the associated web 13.

A mastic material, not shown, may be used to close the slots above elastic material 19 to form a smoother floor, but with or without such mastic filler the floor can be considered uniplanar for all practical purposes. Also, the fioor of the car may be coated with anti-skid material without altering any of the essential relationships of the invention.

In passing between the strips 20, the nail does not rupture the material of the strips but is driven in between two pieces of the material. This feature makes possible the use of an elastic deformable material having a high modulus of elasticity. Examples of suitable materials 19 are relatively hard solid rubber and various elastic deformable plastic materials of relatively high modulus of elasticity in molded or extruded form, such as nylon, polyethylene and the like. Of course, if desired, fiber reinforced materials can be used as the strip materials. Preferably the material should be capable of being strained up to and still maintain substantially complete recovery. It is also preferred that the compressive strength of material 19 at upper yield or 1% offset be about 7,000- 13,000 p.s.i. and that the modulus of elasticity be about 40,000-400,000 p.s.i.

Bridge welds 23 at widely spaced locations on the freight conveying surface of the flooring and the bottom of the nailing slots integrate the tops and bottoms of structural members 9 across the tops and bottoms of the nailing slots between adjacent webs 13, thereby to prevent the webs 13 from pulling away from each other. Of course, bridge welds 23 serve to integrate the flooring members with each other so that not all of the flooring members have to be welded to the conveyance structure as at 16.

The manner of use of the novel flooring according to tions that obtain during the blocking of the freight.

. tion of movement of the conveyance.

the present invention is indicated in FIGURE 3, in which a piece of timber 25 is shown secured to the metallic floorjby means of a nail 27 passing through timber 25 and into the nailing slot between webs 13. The timber in turn serves as a stop to prevent certain classes of freight from shifting about in the car.

. Various important features of the present invention should now be noted. In the first place, it is important to note that the nails are not driven between the strips as though the strips were unconfined blocks of rubber. Instead, the nails are quite close to both of the opposed surfaces of the webs that define the nailing slot. For good results, the diameter of the nail is not less than about half the width of the slot and preferably about 65% to about 85% of the width of the slot. If the nail is too wide, that is, about the same diameter as the width of the slot, then the nail passes so close to both opposed surfaces of the webs defining the slot that the nail cannot make a passageway for itself merely by resiliently compressing or displacing the material 19. Instead, when the nail is too big, material 1% is cut or torn away from the webs at the region where the sides of the nail come closest to or contact the webs. On the other hand, if the slot is too wide, the point of a nail may enter the slot in such a position that it fails to find the valley or cleavage leading into the interface. In other words, the guiding action of the metal shoulders at the entrance of the slot would be lost and a nail could strike directly against the top surface of a strip 20. In such case the nail could be driven only with great difliculty and if driven into the slot would penetrate and tear material 19. Inspection of FIGURE 4 will indicate how the rounded metal shoulders on the structural members 9 at the entrance to the slot can act to guide a nail point toward the cleavage line between strips 20 when the slot is properly dimensioned.

In actual practice the size of the nails and hence the minimum width of the slot are determined by the condi- In blocking freight, it is the practice to use blocks of hardwood such as oak, in various standard sizes such as 2" x 4" and the like. The desired length of the nail is determined by the thickness of the block it passes through so as to leave a reasonable length of nail within the nailing slot to be gripped by material 19. The length of a conventional nail, in turn, largely predetermines its diameter. In the blocking of lading in freight cars and other conveyances, the three most commonly used sizes of nail are 16d, 20d, and 30d. These nails have diameters of 0.162", 0.192" and 0.27", respectively. Smaller than these sizes, too many nails have to be driven to secure the blocking; larger than these sizes, the nails are of such diameter that an ordinary workman has trouble driving them through hardwood with a hand hammer. Considering the manufacturing tolerances of the largest size of nail commonly used and the manufacturing and installation tolerances of the flooring of the present invention, and

\ less, it is possible to use /3" slot or even up to about /2 slot where centering the nail is not a problem. The use of larger slots, however, would inevitably be attended by increased cost of the filling material and the difliculties enumerated above.

Increased width of nailing slot is also undesirable from a standpoint of the manner in which the horizontal stresses applied to the blocking are transmitted to the flooring. In the conveyances of the present invention, the nailing slots extend transversely of the lengthwise extent of the conveyance, that is, transversely of the direc- This means that the horizontal shock and static loads applied to the blocking and transmitted to the flooring are applied largely lengthwise of the conveyance. The present invention, by disposing the nailing slots transverse to the direction of horizontal loading, and by positioning the side walls of the webs closely adjacent the sides of the nails, assures that the strongest horizontal gripping force of the elastic material will be applied to the nail on the sides of the nail adjacent the webs 13, that is, on the sides of the nail which bear the major horizontal loads. The closely spaced webs, acting on the elastic material 19, thus restrain the nail against movement fore and aft of the car,

transversely of the nailing slot.

Moreover, the relationship between the webs and the material in the nailing slots when subjected to compressive forces by the webs must also be emphasized. Whenever downwardly directed forces are imposed on the flooring of the present invention, the webs on opposite sides of the material filling the nailing groove tend to bow toward each other. This is because a couple is present between forces acting parallel to the planes of the webs and forces directed at angles to the planes of the webs and acting through the fillets by which the webs are joined to the horizontal portions of the flooring, or between the forces in the webs and the forces in the horizontal portions themselves. Specifically, any downwardly directed load on the flooring causes vertically directed compressive stresses in the web and also forces in other portions of the flooring disposed at an angle to these web forces, the resultant of these noncoincident forces in effect urging the webs toward each other. Stated another way, the webs behave as though subjected to forces applied perpendicularly to the side of each web opposite its neighboring web across the nailing groove. This tendency to set up a couple, the resultant of which acts to bow the webs toward each other, is of course strongest in cold formed members such as those illustrated in the drawing, in which rounded fillets are necessarily present. The same tendency, however, but in a lesser degree, is also present in extruded or other hot formed members having no fillets by virtue of the asymmetrical design of the web and the attached horizontal portions of the members.

Therefore, it is manifest that in the present invention the presence of the material filling the nailing groove is quite important as this material acts to strengthen the member by resisting the tendency of the webs to bow toward each other. In general, when the material has a relatively low modulus of elasticity, a narrower nail-ing groove is more desirable; while in the case of less readily deformable materials, a wider nailing groove can be tolerated. Movement of the webs toward each other, however, can be permitted up to the elastic limit of the material of the Webs. In the present invention, therefore, much greater loads can be borne without permanent deformation of the flooring by virtue of the presence of elastic material having a high modulus of elasticity in the nailing grooves.

By corollary, the filled nailing groove of the present invention enables theuse of lighter gage, less expensive metal flooring than had heretofore been possible. For example, it has been found that the gage of sheet metal from which flooring is cold rolled can be reduced around 15% without decreasing the strength of the flooring as compared to older and heavier constructions.

FIGURES 6 and 7 show another embodiment of the present invention, in which an elastic deformable element, indicated generally at 29, of still higher modulus of elastici'ty can be used. This is made possible by the incorporation in strips 31, which are similar to strips 20 solid strips 20. In some instances a high starting friction can also be achieved in this manner due to the character of the surface of the material in contact with the nail.

From a consideration of the foregoing description, it will be obvious that all of the initially recited objects of the present invention have been achieved.

The terms floor and flooring as used in the appended claims embrace within their meaning those of the terms wall and walls.

Although the present invention has been described and illustrated in connection with preferred embodiments, it is to be understood that modifications and variations may be resorted to without departing from the spirit of the invention, as those skilled in this art will readily understand. Such modifications and variations are considered to be within the purview and scope of the present invention as defined by the appended claims.

What is claimed is:

1. A structural member for use in freight conveyance floor construction, the member being elongated and having a uniplanar freight-engaging face and a pair of rigid surfaces at either side thereof parallel to each other and extending laterally from the freight-engaging face in the same direction and extending lengthwise of the member and facing away from each other, and solid elastic nailgripping material which is at least predominantly a plastic material and which has a modulus of elasticity in the range of about 40,000 to 400,000 p.s.i. secured to each of said pair of rigid surfaces along at least a major portion of the length of said rigid surfaces and of a width substantially greater than its thickness and extending a substantial distance away from said freight-engaging face and having surfaces on the side of said material opposite said rigid surfaces that are parallel to said rigid surfaces so that when a plurality of the members are secured together side by side with the nail-gripping material of each of a plurality of the members in area contact with the nail-gripping material of at least one other member, adjacent members will define between them a nail-receiving slot bounded by an opposed pair of said rigid surfaces and containing a nail-gripping material characterized by a pair of portions having an interface with each other which is parallel to and spaced between the opposed rigid surfaces.

2. A structural member as claimed in claim 1, the nailgripping material being between A; inch and inch thick.

3. A structural member as claimed in claim 1, the nailgripping material on either side of the member being in the form of a flat strip at least several times wider than it is thick and at least several times longer than it is wide.

4. A structural member as claimed in claim 3, each strip having its edge adjacent the freight-engaging face inclined away from the freight-engaging face in a direction away from its associated member so that when the members are assembled the edges of a pair of contiguous strips will define the sides of a valley for guiding the point of a nail toward said plane of weakness.

5. A structural member as claimed in claim 1, the pair of rigid surfaces being fiat and perpendicular to the freight-engaging face of the member.

6. A construction for use as a freight conveyance floor construction, comprising a plurality of elongated structural members, each structural member having a uniplanar freight-engaging face, the freight-engaging faces of the plurality of structural members being arranged at a uniform level to provide a uniplanar freight-engaging floor surface, each structural member having rigid surfaces at either side thereof extending laterally away from the freight-engaging face, means rigidly securing the structural members together in adjacent side-by-side relation with the rigid laterally extending surfaces of adjacent structural members opposed and contiguous to form a nail-receiving slot therebetween, the opposed rigid surfaces being disposed on opposite sides of a pair of spaced parallel planes that are perpendicular to the freight-engaging fioor surface, thereby to define a slot of a width and of an orientation relative to the freight-engaging floor surface such as to permit a nail to be driven into the slot without deformation of the nail, and solid elastic nail-gripping material which is at least predominantly a plastic material and which has a modulus of elasticity in the range of about 40,000 to 400,000 p.s.i. disposed in the slot and extending a substantial distance away from the freight-engaging floor surface with the opposed rigid surfaces and associated nail-gripping material coacting to restrain the opposed rigid surfaces against extreme movement toward each other and to confine the nail-gripping material against expansion in a direction normal to the opposed rigid surfaces, the nail-gripping material being in the form of a pair of portions having an interface with each other that is disposed between said planes.

7. A construction as claimed in claim 6, the opposed rigid surfaces being fiat and parallel to each other and perpendicular to the freight-engaging floor surface.

8. A construction as claimed in claim 7, the nail-gripping material having a height several times the width of the slot.

9. A construction as claimed in claim 7, said opposed rigid surfaces being spaced apart not less than about onequarter inch and not more than about one-half inch.

10. A construction as claimed in claim 7, the edge of the nail-gripping material remote from the freight-engaging floor surface being unconfined.

11. A construction as claimed in claim 7, the plastic material being rubber.

12. A construction as claimed in claim 7, and means securing one said portion of the nail-gripping material to each of the opposed rigid surfaces.

13. A construction as claimed in claim 7, the nailgripping material extending lengthwise at least a major v portion of the length of the slot.

14. A construction as claimed in claim 7, the upper edges of the two portions of the nail-gripping material defining the sides of a valley for guiding the point of a nail toward said interface.

15. A construction as claimed in claim 7, said interface being parallel to said planes.

16. Railway rolling stock comprising a freight car elongated in its direction of travel and having conveying supporting structure and a floor construction carried thereby to which blocking can be nailed for preventing shifting of freight in transit, the floor construction comprising a plurality of elongated structural members arranged in adjacent side-by-side relation transverse to the length of the freight car, each structural member having a uniplanar freight-engaging face directed away from the conveying supporting structure, the freight-engaging faces of the plurality of structural members being arranged at a uniform level to provide a uniplanar freight-engaging floor surface, the structural members having rigid surfaces at either side thereof extending laterally from adjacent the freight-engaging faces toward the conveying supporting structure, means including rigid connection between the structural members and the conveying supporting structure integrating the floor construction and conveying supporting structure and holding the structural members in side-by-side relation in the freight car with the opposed rigid laterally extending surfaces of adjacent structural members contiguous to form a nail-receiving slot therebetween transverse to the length of the freight car, the opposed rigid surfaces being disposed on opposite sides of a pair of spaced parallel planes that are perpendicular to the freight-engaging floor surface thereby to define a slot of a width and of an orientation relative to the freight-engaging floor surface such as to permit a nail to be driven into the slot without deformation of the nail, and solid elastic nail-gripping material which 9 is at least predominantly a plastic material and which has a modulus of elasticity in the range of about 40,000 to 400,000 p.s.i. disposed in the slot and extending a substantial distance away from the freight-engaging floor surface with the opposed rigid surfaces and associated nail-gripping material coacting to restrain the opposed rigid surfaces against extreme movement toward each other and to confine the nail-gripping material against expansion to a direction normal to the opposed rigid surfaces, the nail-gripping material'being in the form of a 10 pair of portions having an interface with each other that is disposed between said planes.

References Cited in the file of this patent UNITED STATES PATENTS Bronson July 4, 1933 Hatch et a1 Aug. 22, 1939 Meek Sept. 13, 1955 Candlin Mar. 27, 1956 FOREIGN PATENTS Canada June 28, 1960 UNITED STATES PATENT orritr CERTIFICATE F noRREmri Patent No. 3, 132 ,605 May 12 1964 Tappan Collins It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below" Column 7, line 60, for "plane of weakness" read interface Signed and sealed this 6th day of October 1964.

SEAL A test:

ERNEST W0 SWIDER EDWARD J BRENNER Attesting @fficer Commissioner of Patents 

1. A STRUCTURAL MEMBER FOR USE IN FREIGHT CONVEYANCE FLOOR CONSTRUCTION, THE MEMBER BEING ELONGATED AND HAVING A UNIPLANAR FREIGHT-ENGAGING FACE AND A PAIR OF RIGID SURFACES AT EITHER SIDE THEREOF PARALLEL TO EACH OTHER AND EXTENDING LATERALLY FROM THE FREIGHT-ENGAGING FACE IN THE SAME DIRECTION AND EXTENDING LENGTHWISE OF THE MEMBER AND FACING AWAY FROM EACH OTHER, AND SOLID ELASTIC NAILGRIPPING MATERIAL WHICH IS AT LEAST PREDOMINANTLY A PLASTIC MATERIAL AND WHICH HAS A MODULUS OF ELASTICITY IN THE RANGE OF ABOUT 40,000 TO 400,000 P.S.I. SECURED TO EACH OF SAID PAIR OF RIGID SURFACES ALONG AT LEAST A MAJOR PORTION OF THE LENGTH OF SAID RIGID SURFACES AND OF A WIDTH SUBSTANTIALLY GREATER THAN ITS THICKNESS AND EXTENDING A SUBSTANTIAL DISTANCE AWAY FROM SAID FREIGHT-ENGAGING FACE AND HAVING SURFACES ON THE SIDE OF SAID MATERIAL OPPOSITE SAID RIGID SURFACES THAT ARE PARALLEL TO SAID RIGID SURFACES SO THAT WHEN A PLURALITY OF THE MEMBERS ARE SECURED TOGETHER SIDE BY SIDE WITH THE NAIL-GRIPPING MATERIAL OF EACH OF A PLURALITY OF THE MEMBERS IN AREA CONTACT WITH THE NAIL-GRIPPING MATERIAL OF AT LEAST ONE OTHER MEMBER, ADJACENT MEMBERS WILL DEFINE BETWEEN THEM A NAIL-RECEIVING SLOT BOUNDED BY AN OPPOSED PAIR OF SAID RIGID SURFACES AND CONTAINING A NAIL-GRIPPING MATERIAL CHARACTERIZED BY A PAIR OF PORTIONS HAVING AN INTERFACE WITH EACH OTHER WHICH IS PARALLEL TO AND SPACED BETWEEN THE OPPOSED RIGID SURFACES. 